Welding is a common method in order to connect components made of weldable material to each other, as for example components made of steel. Exemplary welding methods are resistance spot welding and stud welding, wherein two opposing components are connected to each other selectively or point by point by means of welding. A further welding method is the stud welding with electric arc.
In various industrial areas, components have to be connected to each other which partly consist of a non- or poorly weldable material. Nevertheless, welding is an effective connection method even for the components made of non- or poorly weldable material. For this purpose, a welding auxiliary joining part made of a weldable material is fastened into the component made of non- or poorly weldable material. Subsequently, a welding connection between a component made of weldable material and the welding auxiliary joining part is produced so that the component made of weldable material and the component made of a non- or poorly weldable material are connected to each other via the welding auxiliary joining part. Examples for components made of non- or poorly weldable material are sheets from aluminum, molded parts made of plastic or fiber-reinforced plastic as for example carbon-fiber-reinforced plastic, to name just a few examples. The above described method follows for example from the German patent application DE 100 15 713 A1.
A similar connection method by means of welding between a component made of non- or poorly weldable material and a component made of weldable material is described in the German patent application DE 10 2005 006 253 A1. In this document, a stud having a shank and a head made of weldable material is inserted into a pre-fabricated hole in the component made of non- or poorly weldable material and is subsequently welded to the component made of weldable material. To fix the stud with its shank in the pre-punched portion of the component made of non- or poorly weldable material reliably, the shank of the stud is laterally deformed after the welding by means of compressing so that a positive or frictional connection between the shank of the stud and the inner wall of the hole of the component results. Due to the plurality of method steps, the connection method described above is technically complex and time consuming.
In the German patent applications DE 10 2004 025 492 A1 and DE 10 2007 036 416 A1, rivets, studs or nails, respectively, are used as welding auxiliary joining part in components made of non- or poorly weldable material. The tip of the welding auxiliary joining part protrudes from the one side of the component made of non- or poorly weldable material and forms a weld spot with a very small contact surface for contacting the opposite component made of a weldable material. As soon as the welding auxiliary joining part and the component made of weldable material are connected to each other, for example by means of resistance welding in the manner of the resistance spot welding or the resistance stud welding, the tip or edge of the welding auxiliary joining part is melted so that a so-called weld nugget results. Due to the small contact surface between the welding auxiliary joining part and the component made of weldable material at the tip or in the cutting area of the welding auxiliary joining part, the contact area for welding is relatively small. This prolongs the welding process or degrades the weld connection due to the small contact surface compared to components arranged opposite to each other, which contact each other in a larger area. Corresponding to the small contact portion between the welding auxiliary joining part and the component made of weldable material, the formed weld nugget is small. This affects, among others, the mechanical load capacity as well as the lifetime of the produced connection. Further, when using a semi-hollow punch rivet as welding auxiliary joining part, a waste slug made of non- or poorly weldable material is created. During the subsequent welding, this slug is arranged in the welding area and in the area of the weld nugget so that the resulting weld connection is affected in its quality due to this contamination.
Further, in DE 10 2004 025 492 A1 it is seen as an advantage to mechanically deform the component made of weldable material in the contact area for the future welding by means of the setting procedure of the welding auxiliary joining part into the component made of non- or poorly weldable material. Especially, a tip or an edge of the welding auxiliary joining part enters the component made of weldable material or creates a recess in this component made of weldable material. This recess shall then facilitate or support the formation of a sufficiently large weld nugget during the resistance welding between the welding auxiliary joining part and the component made of weldable material in the area of this depression or recess, respectively. For realizing this method, however, it is necessary to arrange all components to be connected above each other before the welding auxiliary joining part is set. Otherwise, an additional amount of work is necessary to create the recess in the component made of weldable material and to align it with respect to the welding auxiliary joining parts already set. This is complex, time consuming and further requires additional installation effort for positioning the components to be connected to each other and is limited in the choice of the possible welding methods and the process orders.
It is therefore the object of the present invention to provide a less time consuming connection method between at least one component made of non-weldable material and at least one component made of weldable material compared to the prior art. It is further an object of the present invention to provide a welding auxiliary joining part for such a method which is easily producible, can be set with low effort and can be used flexibly.